Gascolator

[Jonathan Goodish]

Has anyone used the Steve's Aircraft FAA-PMA gascolator STC on a
Cherokee? I am curious as to whether it is worth the trouble of
changing the stock gascolator to get rid of the whole bail wire fiasco.
Not sure how the drain valve would work, might have to use some fittings.



JKG

[[email protected]]

Jonathan Goodish > wrote:
: Has anyone used the Steve's Aircraft FAA-PMA gascolator STC on a
: Cherokee? I am curious as to whether it is worth the trouble of
: changing the stock gascolator to get rid of the whole bail wire fiasco.
: Not sure how the drain valve would work, might have to use some fittings.

What fiasco? Aside from replacing the gasket every once in awhile is there a
flaw in the original gascolator I'm unaware of?

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Jonathan Goodish]

In article >,
wrote:

> Jonathan Goodish > wrote:
> : Has anyone used the Steve's Aircraft FAA-PMA gascolator STC on a
> : Cherokee? I am curious as to whether it is worth the trouble of
> : changing the stock gascolator to get rid of the whole bail wire fiasco.
> : Not sure how the drain valve would work, might have to use some fittings.
>
> What fiasco? Aside from replacing the gasket every once in awhile is
> there a
> flaw in the original gascolator I'm unaware of?

In my opinion, it is a rather poor design. The bowl requires that the
bail wire hold it securely, and bail wires have been known to jump off
the assembly, threads on the thumb screw get stripped making it
impossible to tighten, etc. Stripped threads appear to be common, and
fuel leaks seem to be common as a result. There are some accidents in
the NTSB database that were caused by the bowl coming off in flight
(resulting in engine failure) due to stripped threads on the bail wire.

The "problems" seem to be due to folks over-torquing the thumb screw in
order to "fix" a bad seal, rather than replacing the gasket.
Occasionally, this over-torquing will actually bend the top of the bowl,
making a good seal impossible even with a good gasket.

My bail wire is still holds the bowl tight, but it is stripped and may
not stay tight forever. The Piper replacement part is $170 just for the
bail wire. If you want the entire gascolator, it's something like $700,
which is just insane. Why not replace it with a better design?




JKG

[[email protected]]

Jonathan Goodish > wrote:
: In my opinion, it is a rather poor design. The bowl requires that the
: bail wire hold it securely, and bail wires have been known to jump off
: the assembly, threads on the thumb screw get stripped making it
: impossible to tighten, etc. Stripped threads appear to be common, and
: fuel leaks seem to be common as a result. There are some accidents in
: the NTSB database that were caused by the bowl coming off in flight
: (resulting in engine failure) due to stripped threads on the bail wire.

: The "problems" seem to be due to folks over-torquing the thumb screw in
: order to "fix" a bad seal, rather than replacing the gasket.
: Occasionally, this over-torquing will actually bend the top of the bowl,
: making a good seal impossible even with a good gasket.

: My bail wire is still holds the bowl tight, but it is stripped and may
: not stay tight forever. The Piper replacement part is $170 just for the
: bail wire. If you want the entire gascolator, it's something like $700,
: which is just insane. Why not replace it with a better design?

I had to replace the top part of my Cherokee's gascolator. The previous owner
"repaired" a crack in the fuel outlet fitting with J-B-Weld. Not exactly a
warm-fuzzy... especially since after we installed the autofuel STC the whole
gascolator is pressurized by the electric fuel pump.

I'll agree that it's a minimalist design. Properly cared for it's fine,
though.... just the everything is old enough now to have seen abuse. Since the
bone-fide Piper part is astronomically overpriced (even in *AIRPLANE* dollars!), I'll
agree that the PMA'd replacement looks good. My only concern (as a stock part) would
be that it looks more solid than the original... i.e. heavier. Back when Piper
designed these suckers, they were pretty careful to minimize weight everywhere they
could.

As far as your fuel sumper, you'll need to think about that carefully. I know
there's an AD or SB or something requiring a stopper on the sumper so it cannot be
left open. There have been accidents caused by people draining samples and leaving
the stopcock locked open. Gascolator empties in the sample checker, but stays locked
open... no more fuel in the gascolator indicate it's open. Anyway, you'll probably
have to rig in some plumbing to get all that to go from the looks of it. The Piper
bowl is kinda nice on the side like that. Gives one plenty of adjustment to position
the nozzle by turning the bowl AND adjusting the threads.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Jay Masino]

wrote:
> Jonathan Goodish > wrote:
> : Has anyone used the Steve's Aircraft FAA-PMA gascolator STC on a
> : Cherokee? I am curious as to whether it is worth the trouble of
> : changing the stock gascolator to get rid of the whole bail wire fiasco.
> : Not sure how the drain valve would work, might have to use some fittings.
> What fiasco? Aside from replacing the gasket every once in awhile is there a
> flaw in the original gascolator I'm unaware of?


In addition to Jonathan's comments, the "base" (the top part) of original
Cherokee gascolator has a tendency to warp. Once that happens, no amount
of tightening of the thumbscrew provides a good seal. The new Piper part
has a much beefier base, and shouldn't have the warping problem. I'm not
familiar with the alternate gascolator referred to in Jonathan's original
post.

--- Jay



--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.OceanCityAirport.com
http://www.oc-Adolfos.com

[Jonathan Goodish]

In article >,
wrote:
> I'll agree that it's a minimalist design. Properly cared for it's fine,
> though.... just the everything is old enough now to have seen abuse. Since
> the
> bone-fide Piper part is astronomically overpriced (even in *AIRPLANE*
> dollars!), I'll
> agree that the PMA'd replacement looks good. My only concern (as a stock
> part) would
> be that it looks more solid than the original... i.e. heavier. Back when
> Piper
> designed these suckers, they were pretty careful to minimize weight
> everywhere they
> could.

"Minimalist" is kind... I think it's a rather poor design, especially
for aircraft.

The PMA part is aluminum, so it can't be that much heavier, and I hardly
think that this is an area where weight should take priority over safety.

I am going to call and talk to the STC owner and see what he tells me.
You are correct, it looks like there will need to be some plumbing to
get the drain to exit the cowling properly. If the latter can't be
accomplished gracefully, then this may not be a good solution after all.

The problem with the sump valve being left open is operator error and
not a design flaw. Personally, I scan all sump valves before flight to
ensure that there are no leaks. There might be a SB, but I am not aware
of any AD relating to this issue that applies to my aircraft, and we've
done a pretty comprehensive search of ADs over the years.





JKG

[[email protected]]

Jonathan Goodish > wrote:
: "Minimalist" is kind... I think it's a rather poor design, especially
: for aircraft.

It's right on-par with everything else designed at that point in time.
Exactly the same gascolator is on my dad's 1939 Oliver 60 Row Crop tractor, except it
has a clear glass bowl. They "ruggedized" it for aircraft useage by using an aluminum
bowl... :)

: The PMA part is aluminum, so it can't be that much heavier, and I hardly
: think that this is an area where weight should take priority over safety.

It looks like it's machined out of a solid piece, rather than cast. It looks
heavier (and ironically much more expensive to produce).

: I am going to call and talk to the STC owner and see what he tells me.
: You are correct, it looks like there will need to be some plumbing to
: get the drain to exit the cowling properly. If the latter can't be
: accomplished gracefully, then this may not be a good solution after all.

: The problem with the sump valve being left open is operator error and
: not a design flaw. Personally, I scan all sump valves before flight to
: ensure that there are no leaks. There might be a SB, but I am not aware
: of any AD relating to this issue that applies to my aircraft, and we've
: done a pretty comprehensive search of ADs over the years.

It is and isn't operator error. Many of them (like mine) cannot be easily
seen... it's tucked up within the cowling and is only accessed via a 1" hole. Also,
you could scan for leaks all you want... if the gascolator has been drained of all
fuel by sumping to a sample jar, it won't leak even if it's locked open. That's the
substance of the AD/SB or whatever I heard.

I would think you could get the drain with a 90 degree 1/8" NPT elbow and
perhaps a small extension. My plane has a 45 degree on the stock bowl. If it's PMA'd
for the PA-28, it *should* fit right in. If not it should have approved data (i.e.
STC or standard AN part via AC43).

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Jonathan Goodish]

In article >,
wrote:
> It's right on-par with everything else designed at that point in time.
> Exactly the same gascolator is on my dad's 1939 Oliver 60 Row Crop tractor,
> except it
> has a clear glass bowl. They "ruggedized" it for aircraft useage by using an
> aluminum
> bowl... :)

That design is fine on a tractor, but is not so great on an aircraft.
It's amazing what junk some of these aircraft manufacturers used (and
had certificated). They couldn't get away with the glass bowl, but they
did the minimum required to make it work to get the airplane
certificated.



> It is and isn't operator error. Many of them (like mine) cannot be easily
> seen... it's tucked up within the cowling and is only accessed via a 1" hole.
> Also,
> you could scan for leaks all you want... if the gascolator has been drained
> of all
> fuel by sumping to a sample jar, it won't leak even if it's locked open.

It isn't necessary to drain the gascolator completely. In fact, when I
was a student pilot, I was taught to activate the fuel boost pump while
sumping, which would ensure that you couldn't accidentally drain the
gascolator. I think this is overkill and I no longer do this, but it's
probably not bad advice for a student pilot.



> I would think you could get the drain with a 90 degree 1/8" NPT elbow and
> perhaps a small extension. My plane has a 45 degree on the stock bowl. If
> it's PMA'd
> for the PA-28, it *should* fit right in. If not it should have approved data
> (i.e.
> STC or standard AN part via AC43).

I did call and talk to the guy this morning. He said that, in most
cases, the 90 degree fitting and extension usually does the job, but in
some cases, folks have remote mounted the valves. I don't want to
remote mount mine, so I might go take some measurements to make an
initial determination as to whether it will fit.

The bottom line is that if I elect to keep the Piper gascolator, I'm
stuck paying almost as much for just the bail wire as for the entire STC
gascolator unit. I'm sure that you can see why this is of such
interest, and I'm surprised that it hasn't received more attention.



JKG

[[email protected]]

: That design is fine on a tractor, but is not so great on an aircraft.
: It's amazing what junk some of these aircraft manufacturers used (and
: had certificated). They couldn't get away with the glass bowl, but they
: did the minimum required to make it work to get the airplane
: certificated.

That's true, but there's history involved. Lots of manufacturers' parts were
made cheaply as commodity parts at the time. Those were then grandfathered in to new
designs, unless there was some reason to change them. IIRC, O-rings weren't even
common until after WWII... the rubber washer in the gascolator is more old-school and
predates WWII. An airplane is generally better built than a tractor, but a 1939
tractor and a 1939 Piper are more similar than different. Don't confuse "junk" with
"old technology" or "inexpensive construction." They're not necessarily synonyms. I
would (and apparently am) arging that the original gascolator is perfectly adequate
unless abused (e.g. warped top, bad seals, stripped threads, etc).

: It isn't necessary to drain the gascolator completely. In fact, when I
: was a student pilot, I was taught to activate the fuel boost pump while
: sumping, which would ensure that you couldn't accidentally drain the
: gascolator. I think this is overkill and I no longer do this, but it's
: probably not bad advice for a student pilot.

OK, you got me. Draining the gascolator could be considered operator error as
well. It doesn't have to be done, but some people do it anyway. In any event, since
when has regulation made sense? (Since my gascolator is pressurized now with the fuel
pump on, it *really* squirts out if you sample then)

: I did call and talk to the guy this morning. He said that, in most
: cases, the 90 degree fitting and extension usually does the job, but in
: some cases, folks have remote mounted the valves. I don't want to
: remote mount mine, so I might go take some measurements to make an
: initial determination as to whether it will fit.

I wouldn't relocate either... KISS. More parts, fittings, mounts to fail.

: The bottom line is that if I elect to keep the Piper gascolator, I'm
: stuck paying almost as much for just the bail wire as for the entire STC
: gascolator unit. I'm sure that you can see why this is of such
: interest, and I'm surprised that it hasn't received more attention.

I agree completely for your situation. The original post seemed to imply a
rampant and persistant problem with these old gascolators. I didn't know it was
rampant.

You may want to look at salvage yards. Also, since it *is* just a piece of
wire, you can fabricate one yourself ("owner-fabricated parts") if your A&P/IA is OK
with it.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Mike Ferrer]

"Jonathan Goodish" > wrote in message
...
> Has anyone used the Steve's Aircraft FAA-PMA gascolator STC on a
> Cherokee? I am curious as to whether it is worth the trouble of
> changing the stock gascolator to get rid of the whole bail wire fiasco.
> Not sure how the drain valve would work, might have to use some fittings.
>
> JKG

Yes, I put one on my Dakota several years ago. Good product, excellent
quality.

Mike

[Jay Honeck]

> My only concern (as a stock part) would
> be that it looks more solid than the original... i.e. heavier. Back when
> Piper
> designed these suckers, they were pretty careful to minimize weight
> everywhere they
> could.

That's true. Karl Bergey, one of the designers of the Cherokee, told us
that Pug Piper had a hard and fast rule: You could only add weight
somewhere if you first reduced weight somewhere else.

Which is how we all ended up with those classy "Royalite" interiors!

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"